1. Field of the Invention
This invention relates to permanent, ultrasonic, flexible, dry-coupled, linear arrays for the inspection of pipelines, process equipment, and the like. The permanent, ultrasonic, flexible, dry-coupled, linear arrays detect and/or measure corrosion wall loss, stress corrosion cracking, and/or internal initiated pipeline cracking.
2. Discussion of Related Art
Conventional ultrasonic sensors have high manufacturing costs and have coupling issues or problems resulting in loss of signal or inaccurate readings. Good ultrasonic sound transmission depends upon removing all air between the sensor and a test surface. Sufficient readings and/or measurements involve the ultrasonic sensor transmitting and receiving a signal with minimal signal loss and/or degradation, such as without air bubbles and/or gaps. Ultrasonic sensors typically use a couplant to increase transmission between a test material and the sensor. Conventional liquid couplants include propylene glycol or glycerin. The liquid couplant dries, leaks, and/or runs out from the under the sensor which causes signal problems. Liquid couplants provide a temporary or short duration of suitable acoustic transmission. Cawley et al., International Patent Application Publication WO2007/051959 discloses an elongate strip of ultrasound transmissive material.
Attempts in the industry have been made to use magnets or adhesive bonding for ultrasonic energy transmission systems. However, these adhesive bonds have a high failure rate due to bond degradation and fracture over time. The energy input from the ultrasonic sensor may contribute to adhesive failure. Roarty, U.S. Pat. No. 4,881,409 discloses a flexible magnetic material with an array of ultrasonic transducers. Fripp et al., U.S. Pat. No. 7,234,519 discloses an adhesive bonding of transducers to pipe for oil drilling. While magnets or adhesive bonds may provide signal transmission for a longer duration than a liquid couplant before adhesive failure, there is still a need and a desire for ultrasonic sensors that can be installed for longer and/or permanent durations.